The present invention relates to a glass panel with an improved heat-insulating property as compared with ordinary plate glass, and a manufacturing method thereof. More particularly, the present invention relates to a glass panel including numerous spacers interposed between a pair of plate glasses, an outer peripheral closing portion provided between outer peripheries of the pair of plate glasses, and a sucking portion provided in one plate glass of the pair of plate glasses for vacuum-closing a void portion between the two plate glasses, and to a method of manufacturing a glass panel in which the glass panel is formed by sealing the sucking the portion after sucking gas in the void portion through the sucking portion.
Conventionally, as this kind of a glass panel, there is known a glass panel in which a sucking portion 3 is constructed by fixing a glass tube 21 to a sucking mouth 1a formed in one plate glass 1A for communication, and a protruding tip end 21a of the glass tube 21 is formed to be capable of being closed by heat melting, as shown in FIG. 23 and FIG. 24.
Further, in a method for forming this kind of a glass panel, a glass tube 21 is fixed to the sucking mouth la for communication as shown in FIG. 23; the void portion V is vacuumized by suction through the glass tube 21; and the protruding tip end 21a is melted by heating to close an opening of the end of the glass tube, as shown in FIG. 24.
However, according to the above-mentioned conventional glass panel and method for forming a glass panel, the glass tube 21 remains in a protruding state on a surface of the plate glass 1A in the sucking portion 3, whereby appearance tends to be deteriorated. Also, there is a problem that other objects are likely to collide with the glass tube 21 and destruction of the sucking portion 3 caused by strong external force exerted on the glass tube 21 deteriorates the vacuum state of the void portion V to decrease the heat-insulating property as a glass panel.
Further, use of a cap for protection of the protruding portion of the glass tube 21 further deteriorates the appearance more.
Therefore, the purpose of the present invention is to provide a glass panel and a method for manufacturing the same in which the above-mentioned problems are solved, and the collision and the like of other objects against the sucking portion is avoided, with reduced deterioration of the appearance.
The characteristic constructions of the glass panel and the method for manufacturing the same are as follows.
A glass panel according to claim 1 is a glass panel including numerous spacers interposed between a pair of plate glasses, an outer peripheral closing portion provided between outer peripheries of the two plate glasses, and a sucking portion provided in one plate glass of the pair of plate glasses for vacuum-closing a void portion between the two plate glasses, as exemplified in FIG. 2 and FIG. 16 to FIG. 20.
Particularly, in constructing the sucking portion, a sucking mouth is provided in the one plate glass, and a closing plate is disposed to lie along a plane of the one plate glass for covering the sucking mouth. The plate glass and the closing plate are integrated by a bonding portion disposed between the plate glass and the closing plate.
According to this construction, the closing plate can seal the sucking portion with an extremely small amount of protrusion on the surface of the one plate glass. Therefore, it is easier to prevent breakage of the sucking portion caused by another object abutting to or being caught by the sucking portion, as compared with the conventional one.
As a result, the facility in handling the glass panel is improved, and the heat insulating property can be maintained more easily. Further, since the amount of protrusion from the surface of the plate glass is small, the sucking portion is less likely to be conspicuous and the deterioration of the appearance as a glass panel can be prevented more easily.
In the invention according to claim 2, the bonding portion can be constructed with a bonding member having a melting point within a temperature range lower than a softening point of the plate glass and higher than an ambient temperature of use of the plate glass; and the closing plate can be constructed with a closing member having a melting point higher than the bonding portion, as shown in FIG. 2.
This construction produces the following effect in addition to the function and effect produced by the invention of claim 1.
Namely, the closing member and the one plate glass can be bonded with each other integrally and in close contact by solidification of the bonding member by raising the ambient temperature of the sucking portion with the bonding member and the closing member superposed on the sucking portion for melting the bonding member and then lowering the ambient temperature.
Accordingly, the bonding step can be carried out simply by controlling the temperature of the sucking portion either in an environment of atmospheric pressure or in an environment of reduced pressure, whereby the selectivity of the working environment can be improved, and it can be adapted to various glass panel manufacturing methods carried out under various environments.
In a glass panel according to claim 3, a ring-shaped metal plate can be interposed between the plate glass and the closing plate; and the bonding portion can be constructed with a low melting point glass sintered layer integrally interposed between a surface of the plate glass on an edge of the sucking mouth and the ring-shaped metal plate, and with a solder layer integrally interposed between the ring-shaped metal plate and the closing plate, as shown in FIG. 16 and FIG. 17.
This construction produces the following effect in addition to the function and effect produced by the invention of claim 1.
For example, it is possible to adopt a method of sealing the sucking portion in which the bonding portion made of a low melting point glass sintered layer is formed under an environment of atmospheric pressure, and the bonding portion made of the solder layer is formed under an environment of reduced pressure.
Incidentally, the low melting point glass sintered layer is formed by sintering a low melting point glass and, if the temperature is raised under an environment of reduced pressure, there is a problem that a gas is generated from the low melting point glass to deteriorate the efficiency of hermetic closing between the two plate glasses. However, in the case of the glass panel of this construction, the bonding portion made of the low melting point glass sintered layer can be formed under an environment of atmospheric pressure, so that the low melting point glass can be used without hindrance. As a result of this, another object can be bonded to the glass in a more stable state.
Further, after the ring-shaped metal plate is bonded to the plate glass by the low melting point glass sintered layer, the bonding portion made of the solder layer can bond the closing plate further more strongly under an environment of reduced pressure with no generation of gas from the low melting point glass sintered layer. As a result of this, the sucking portion can be sealed without adopting a sophisticated method.
Here, the ring shape as referred to in the shape of the metal plate is not limited to a circular ring shape, but may be a polygonal ring shape or a ring shape with non-specified shape. These shapes as a whole are referred to as a ring shape.
In a glass panel according to claim 4, the closing plate can be constructed with a second solder plate; a ring-shaped metal plate can be interposed between the plate glass and the closing plate; and the bonding portion can be constructed with a low melting point glass sintered layer integrally interposed between a surface of the plate glass on an edge of the sucking mouth and the ring-shaped metal plate, as shown in FIG. 18 to FIG. 20.
This construction produces the following effect in addition to the function and effect produced by the invention of claim 1.
According to this construction, for example, after the ring-shaped metal plate is bonded to the plate glass by the bonding portion made of a low melting point glass sintered layer under an environment of atmospheric pressure, the second solder plate can be mounted on the ring-shaped metal plate and the temperature can be raised under an environment of reduced pressure to melt the second solder plate for integration with the ring-shaped metal plate, thereby to seal the sucking portion.
In other words, as in the previously mentioned case, the low melting point glass sintered layer can be formed while avoiding the inconvenience of poor efficiency of closing between the two plates caused by generation of gas, so that another object can be bonded to the glass plate in a more stable state. Further, after the ring-shaped metal plate is bonded to the plate glass by the low melting point glass sintered layer, the temperature of the closing plate made of the second solder plate can be raised under a reduced pressure to close the sucking portion together with the ring-shaped metal plate, thereby facilitating the sealing of the sucking portion.
In a glass panel according to claim 5, a precious metal layer can be provided on a surface of the ring-shaped metal plate that faces the closing plate, as shown in FIG. 16 and FIG. 18.
If a precious metal layer is disposed on a surface of the ring-shaped metal plate on the closing plate side, the adhesion strength of the closing plate to be adhered to the surface can be increased, so that the degree of vacuum in the void portion can be maintained for a long period of time.
A glass panel according to claim 6 is directed to a method of manufacturing a glass panel using a glass panel body including numerous spacers interposed between a pair of plate glasses, an outer peripheral closing portion provided between outer peripheries of the two plate glasses; and a sucking portion provided in one plate glass of the pair of plate glasses for vacuum-closing a void portion between the two plate glasses, the glass panel being formed by sealing the sucking portion after sucking gas in the void portion through the sucking portion, characterized in that a surface of an edge portion of a sucking mouth of the one plate glass is metallized in a ring shape in advance; and a solder plate and a closing plate made of a metal are placed in superposition on the metallized portion and heated to melt the solder plate for integrating the plate glass with the closing plate, as shown in FIG. 3 to FIG. 13.
According to this means, since the solder plate is melted on the previously metallized portion, the sturdy closing plate made of metal can be integrated with the plate glass in a close bonded state. Therefore, the reliability of the sucking portion is improved, and the reduced pressure environment in the void portion can be maintained for a long period of time, thereby achieving a glass panel having a high heat-insulating property.
Further, the sucking portion can be sealed in a state of extremely small protrusion from the surface of the plate glass, thereby effectively preventing the generation of inconvenience such as breakage of the sucking portion caused by another object abutting against the sucking portion as well as improving the facility in handling.
Here, the metallizing refers, for example, to forming a layer on a surface of the plate glass by sintering of a silver paste, exerting a supersonic vibration on a solder (direct soldering method), plating, flame spraying, or the like. The metal to be used may be copper or nickel besides silver.
A glass panel according to claim 7 can be constructed using a solder plate that provides a gap between the solder plate and the metallized portion for enabling communication between the void portion and an external space, as shown in FIG. 12 to FIG. 14.
This construction produces the following effect in addition to the function and effect produced by the invention of claim 6.
Namely, the gas can be discharged smoothly and effectively through the gap in vacuumizing the void portion by sucking with the solder plate and the closing plate superposed on the sucking mouth.
Also, it facilitates prevention of displacement of the solder plate or the closing plate from the sucking mouth which displacement is caused by the gas sucked from the void portion to the external space, whereby the sucking portion can be sealed with good precision.